Ramos has been handed a contract with CSKA until the end of their domestic season in December.
CSKA, who are fourth in the Russian Premier League and 10 points behind champions and leaders Rubin Kazan with 10 games to go, sacked Brazil legend Zico before the international break following a defeat by FC Rostov.
"I am very excited because CSKA is a historic team on the Continent,' said Ramos. "I'm here to help, especially in the Champions League. The goal is to get through the group stage since they have never played a knock-out second round match."